Penning-trap mass measurements on <Superscript>92, 94-98, 100</Superscript>Mo with JYFLTRAP

Penning-trap measurements on stable ^{92, 94-98, 100}Mo isotopes have been performed with relative accuracy of \(\ensuremath 1\cdot 10^{-8}\) with the JYFLTRAP Penning-trap mass spectrometer by using ⁸⁵Rb as a reference. The Mo isotopes have been found to be about 3keV more bound than given in the Atomic Mass Evaluation 2003 (AME03). The results confirm that the discrepancy between the ISOLTRAP and JYFLTRAP data for ^101-105Cd isotopes was due to an erroneous value in the AME03 for ⁹⁶Mo used as a reference at JYFLTRAP. The measured frequency ratios of Mo isotopes have been used to update mass-excess values of 30 neutron-deficient nuclides measured at JYFLTRAP.     

High-precision mass measurements of hydrogen-like <Superscript>24</Superscript>Mg<Superscript>11+</Superscript> and <Superscript>26</Superscript>Mg<Superscript>11+</Superscript> ions in a Penning trap

For the determination of the bound-electron g factor in hydrogen-like heavy ions the mass of the ion is needed at a relative uncertainty of at least 1 ppb. With the SMILETRAP Penning trap mass spectrometer at the Manne Siegbahn Laboratory in Stockholm several mass measurements of ions with even-even nuclei at this level of precision have been performed so far, exploiting the fact that the mass precision increases linearly with the ion charge. Measurements of masses of the hydrogen-like ions of the two Mg-isotopes ²⁴Mg and ²⁶Mg are reported. The masses of the hydrogen-like ions are 23.979011054(14) u and 25.976562354(34) u, corresponding to the atomic masses 23.985041690(14) u and 25.982592986(34) u, respectively. The possibility to use these two isotopes for the first observation of an isotope effect in the bound-electron g factor in hydrogen-like heavy ions is discussed.     

Precision mass measurements of radioactive nuclei at JYFLTRAP

The Penning trap mass spectrometer JYFLTRAP was used to measure the atomic masses of radioactive nuclei with an uncertainty better than 10 keV. The atomic masses of the neutron-deficient nuclei around the line were measured to improve the understanding of the rp-process path and the SbSnTe cycle. Furthermore, the masses of the neutron-rich gallium ( ) to palladium ( ) nuclei have been measured. The physics impacts on the nuclear structure and the r-process paths are reviewed. A better understanding of the nuclear deformation is presented by studying the pairing energy around .     

<Superscript>23</Superscript>Na and <Superscript>27</Superscript>Al NMR Study of Structure and Dynamics in Mordenite

Temperature dependencies of ²⁷Al and ²³Na nuclear magnetic resonance spectra and spin–lattice relaxations in mordenite have been studied in static and magic angle spinning regimes. Our data show that the spin–lattice relaxations of the ²³Na and ²⁷Al nuclei are mainly governed by interaction of nuclear quadrupole moments with electric field gradients of the crystal, modulated by translational motion of water molecules in the mordenite channels. At temperatures below 200 K, the dipolar interaction of nuclear spins with paramagnetic impurities becomes an important relaxation mechanism of the ²³Na and ²⁷Al nuclei.     

New measurements on breakup of <Superscript>8</Superscript>B + <Superscript>58</Superscript>Ni at energies around the coulomb barrier

New breakup cross section measurements for ⁸B + ⁵⁸Ni are reported, obtained by detecting the ⁷Be products at forward angles (±45°) for 25.0, 26.9, and 28.4-MeV bombarding energies. The obtained results are consistent with those at 25.75 MeV, measured previously. Continuum-discretized coupled-channel calculations are performed and compared to the data. The text was submitted by the authors in English.     

A study of semi-classical processes in the elastic scattering of <Superscript>32</Superscript>S by <Superscript>64</Superscript>Ni and <Superscript>58</Superscript>Ni by <Superscript>27</Superscript>Al

In order to determine the extent of the presence of semi-classical phenomena such as Fresnel and Fraunhofer patterns etc., we have analyzed the elastic scattering of ³²S by ⁶⁴Ni and ⁵⁸Ni by ²⁷Al using the McIntyre parametrization at several energies. The theoretical approach can reasonably account for the general pattern of the data, thus allowing us to extract the parameters pertinent to these semi-classical processes. The scattering of ⁵⁸Ni by ²⁷Al at 220, 185, 170, 160 and 155 MeV laboratory energies, exhibits features expected from the strong absorption model (SAM). However, the features of the scattering of ³²S by ⁶⁴Ni at 150, 108, 98, 93, 91, 88 and 82 MeV laboratory energies have significant deviation from the expected pattern of SAM.     

A single laser system for ground-state cooling of <Superscript>25</Superscript>Mg<Superscript>+</Superscript>

We present a single solid-state laser system to cool, coherently manipulate and detect ²⁵Mg⁺ ions. Coherent manipulation is accomplished by coupling two hyperfine ground state levels using a pair of far-detuned Raman laser beams. Resonant light for Doppler cooling and detection is derived from the same laser source by means of an electro-optic modulator, generating a sideband which is resonant with the atomic transition. We demonstrate ground-state cooling of one of the vibrational modes of the ion in the trap using resolved-sideband cooling. The cooling performance is studied and discussed by observing the temporal evolution of Raman-stimulated sideband transitions. The setup is a major simplification over existing state-of-the-art systems, typically involving up to three separate laser sources.     

Deuteron scattering on <Superscript>6</Superscript>Li at an energy of 25 MeV

At an energy of 25 MeV and in the angular range 7°−175° in the laboratory frame, angular distributions were measured for elastic deuteron scattering on ⁶Li nuclei and for the respective inelastic-scattering processes accompanied by the transitions to the ground state (1+) of the ⁶Li nucleus and to its excited state at E _x = 2.186 MeV (J ^π = 3⁺). The resulting data were analyzed on the basis of the optical model of the nucleus and the coupled-reaction-channel method with allowance for the mechanism of alpha-particle-cluster exchange. It is shown that only upon including, in the analysis, channel coupling and the exchange mechanism can the experimental cross sections for elastic and inelastic scattering be reproduced over the entire range of angles.     

1<Superscript>+</Superscript>(0<Superscript>+</Superscript>) state at 12.4 MeV in <Superscript>20</Superscript>Ne

Careful review of all the evidence makes it clear that at least three states are important at 12.4-MeV excitation in ²⁰Ne (four, if the broad (2⁺) at 12.5 MeV is included). The three states are 3 ^- , 0 ⁺ , and 1 ⁺ (0⁺). The latter, which is quite strong in ¹⁹F (³He, d) singles, is probably the state observed in coincidence with 6.13-MeV γ-rays in ¹⁹F(³He, dγ). Received: 19 August 2002 / Accepted: 28 October 2002 / Published online: 17 January 2003 RID="a" ID="a"e-mail: fortune@physics.upenn.edu Communicated by D. Guerreau     

<Superscript>29</Superscript>Si, <Superscript>27</Superscript>Al, <Superscript>1</Superscript>H and <Superscript>23</Superscript>Na MAS NMR Study of the Bonding Character in Aluminosilicate Inorganic Polymers

²⁹Si, ²⁷Al, ¹H and ²³Na solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) has been used to relate nominal composition, bonding character and compressive strength properties in aluminosilicate inorganic polymers (AIPs). The ²⁹Si chemical shift varies systematically with Si-to-Al ratio, indicating that the immediate structural environment of Si is altering with nominal composition. Fast ¹H MAS and ²⁹Si T _SiH/T _1ρ relaxation measurements demonstrated that occluded pore H₂O mobility within the disordered cavities is slow in comparison with H₂O mobility characteristics observed within the ordered channel structures of zeolites. The ²⁷Al MAS NMR data show that the Al coordination remains predominantly 4-coordinate. In comparison with the ²⁹Si MAS data, the corresponding ²⁷Al MAS line shapes are relatively narrow, suggesting that the AlO₄ tetrahedral geometry is largely unperturbed and the dominant source of structural disorder is propagated by large distributions of Si–O bond angles and bond lengths. Corresponding ²³Na MAS and multiple-quantum MAS NMR data indicate that Na speciation is dominated by distributions of hydration states; however, more highly resolved ²³Na resonances observed in some preparations supported the existence of short-range order. New structural elements are proposed to account for the existence of these Na resonances and an improved model for the structure of AIPs has also been proposed. Authors' address: John V. Hanna, NMR Facility, Institute of Materials and Engineering Science, Lucas Heights Research Laboratories, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia     

Dynamic polarization potentials for <Superscript>6</Superscript>He + <Superscript>209</Superscript>Bi and <Superscript>11</Superscript>Li + <Superscript>208</Superscript>Pb systems at near-barrier energies

The Coulomb dipole induced dynamic polarization potentials for ⁶He + ²⁰⁹Bi and ¹¹Li + ²⁰⁸Pb systems within the framework of Feshbach’s formalism with a motive to ascertain the presence or absence of threshold anomaly have been studied. As a result of this study, the threshold anomaly has been found to be present for both systems. It has also been found that at deep sub-barrier energies the imaginary part either starts increasing or at least remains unchanged which indicates the presence of the breakup threshold anomaly. In addition, the Coulomb breakup transmission factors for both systems have been found to have maximum value below and near-barrier energies, but at very high energies due to closure of the breakup channel the breakup transmission coefficients quickly becomes zero.     

Analysis of <Superscript>8</Superscript>B Proton Halo Nucleus Scattered from <Superscript>12</Superscript>C and <Superscript>58</Superscript>Ni at Different Energies

Angular distributions in the elastic scattering of ⁸B from ¹²C and ⁵⁸Ni targets at different energies have been analyzed in the framework of the double-folding (DF) optical model. The real central part of the nuclear optical potential is obtained by folding the M3Y effective interaction with the cluster density distribution of the ⁸B nucleus. The experimental angular distributions have been successfully reproduced. This confirms the validity of the cluster structure of the ⁸B nucleus.     

Precision electron-gamma spectroscopic measurements in <Superscript>75</Superscript>As

The decay of ⁷⁵Se to levels of ⁷⁵As has been studied using an HPGe detector for gamma-ray and a mini-orange electron spectrometer for conversion electron measurements. We identify 38 transitions in this decay, including 18 gamma rays and 16 conversion electron lines reported for the first time. New results also include E2 multipolarity assignment for the 81 keV transition, M1 assignment to three newly observed transitions and M1 + E2 for the 617 keV transition. A revised ⁷⁵As level scheme is constructed using the Ritz combination principle through the computer code GTOL. While confirming the existence of 10 well-established levels, two levels at 587 and 859 keV are newly placed into the decay scheme of ⁷⁵Se. The interpretation of the observed levels in terms of various theoretical approaches is briefly discussed. The newly placed 586.8 keV 1/2^- and 859.9 keV 1/2⁺ levels are studied in the light of the Interacting Boson-Fermion Model.     

Isotopomer selective optimization of <Superscript>39</Superscript>K<Superscript>85</Superscript>Rb<Superscript>+</Superscript> and <Superscript>41</Superscript>K<Superscript>87</Superscript>Rb<Superscript>+</Superscript> using optimal control

We report on isotope selective three-photon ionization of two isotopomers of KRb by applying evolution strategies. The particularity of this experiment is based on the high resolution phase and amplitude modulation of the fs-laser pulses provided by a 2 × 640 pixel pulse shaper. The optimization in a closed feedback loop performed with spectrally broad pulses centered at 840 nm shows high enhancements of one isotopomer at the expense of the other isotopomer and vice versa. From the optimal laser field we aim to gain details about the selective ionization sequence and the wavepacket evolution on the involved vibrational states.     

Charged particle spectra upon interaction between 50.5 MeV <Superscript>3</Superscript>He ions and <Superscript>27</Superscript>Al nuclei

The inclusive spectra of light charged particles formed upon interaction between 50.5 MeV ³Не ions and ²⁷Al nuclei are studied. The experimental results are analyzed using the exciton model of nucleus decay, with the PRECO-2006 code describing the transition of an excited system to equilibrium state. The contributions from composite, pre-equilibrium, and direct processes of integral cross section formation are calculated. Determination of these mechanisms is of interest to both fundamental nuclear physics and different areas of application, particularly the nuclear transmutation of long-lived radioactive contamination.